Thanks Daniel, I will take a look probably tommorow or on Wednesday.

Cheers,

Olivier

> On 11 Sep 2017, at 18:56, Daniel Egana-Ugrinovic <email address hidden> wrote:
> 
> Public bug reported:
> 
> Hi,
> 
> When showering with Pythia8 with just one core, showering fails. The
> error one gets is
> 
> Pythia8 cross-section could not be retreived.
> Try turning parallelization off by setting the option nb_core to 1.
> 
> The given message doesn't make sense, since I am actually running on a
> single core. Strangely, the problem only arises when working with only
> one core, with generate_events --nb_core=1. Using generate_events
> --nb_core=2 fixes the issue (unfortunately, when running on clusters,
> system administrators usually ask you to avoid multi-threaded code, so
> in those cases using nb_core=2 would not help). The problem may be that
> the file unweighted_events.lhe is not being compressed into a gzip file
> unweighted_events.lhe.gz. Since run_shower.sh seems to need a gzipped
> lhe file, showering fails.
> 
> Further information:
> Options are set in mg5 with
> set run_mode 2
> set nb_core 1
> save options
> 
> Events are being run with madevent:
> generate_events runname --nb_core=1
> shower=PYTHIA8
> 
> Technical details:
> Running madgraph 2.6.0
> Pythia8
> Python 2.7.13
> gcc (GCC) 6.2.0
> 
> I attach the MG5 output file
> 
> Thanks!
> 
> Daniel
> 
> ** Affects: mg5amcnlo
>     Importance: Undecided
>         Status: New
> 
> ** Attachment added: "MG5outputrun_yL_0.5_DM_2.0_MFc_60.0_Mphi_110.0_run0"
>   https://bugs.launchpad.net/bugs/1716425/+attachment/4948030/+files/MG5outputrun_yL_0.5_DM_2.0_MFc_60.0_Mphi_110.0_run0
> 
> ** Description changed:
> 
>  Hi,
> 
>  When showering with Pythia8 with just one core, showering fails. The
>  error one gets is
> 
>  Pythia8 cross-section could not be retreived.
>  Try turning parallelization off by setting the option nb_core to 1.
> 
> - The given message doesn't make sense, since I am actually running on
> - single core mode. Strangely, the problem only arises when working with
> - only one core, with generate_events --nb_core=1. Using generate_events
> + The given message doesn't make sense, since I am actually running on a
> + single core. Strangely, the problem only arises when working with only
> + one core, with generate_events --nb_core=1. Using generate_events
>  --nb_core=2 fixes the issue (unfortunately, when running on clusters,
>  system administrators usually ask you to avoid multi-threaded code, so
>  in those cases using nb_core=2 would not help).
> 
>  Further information:
>  Options are set in mg5 with
>  set run_mode 2
>  set nb_core 1
>  save options
> 
>  Events are being run with madevent:
>  generate_events runname --nb_core=1
> - shower=PYTHIA8 
> + shower=PYTHIA8
> 
>  Technical details:
>  Running madgraph 2.6.0
>  Pythia8
>  Python 2.7.13
>  gcc (GCC) 6.2.0
> 
>  I attach the MG5 output file
> 
>  Thanks!
> 
>  Daniel
> 
> -- 
> You received this bug notification because you are subscribed to
> MadGraph5_aMC@NLO.
> https://bugs.launchpad.net/bugs/1716425
> 
> Title:
>  Showering does not work when running with nb_core=1
> 
> Status in MadGraph5_aMC@NLO:
>  New
> 
> Bug description:
>  Hi,
> 
>  When showering with Pythia8 with just one core, showering fails. The
>  error one gets is
> 
>  Pythia8 cross-section could not be retreived.
>  Try turning parallelization off by setting the option nb_core to 1.
> 
>  The given message doesn't make sense, since I am actually running on a
>  single core. Strangely, the problem only arises when working with only
>  one core, with generate_events --nb_core=1. Using generate_events
>  --nb_core=2 fixes the issue (unfortunately, when running on clusters,
>  system administrators usually ask you to avoid multi-threaded code, so
>  in those cases using nb_core=2 would not help). The problem may be
>  that the file unweighted_events.lhe is not being compressed into a
>  gzip file unweighted_events.lhe.gz. Since run_shower.sh seems to need
>  a gzipped lhe file, showering fails.
> 
>  Further information:
>  Options are set in mg5 with
>  set run_mode 2
>  set nb_core 1
>  save options
> 
>  Events are being run with madevent:
>  generate_events runname --nb_core=1
>  shower=PYTHIA8
> 
>  Technical details:
>  Running madgraph 2.6.0
>  Pythia8
>  Python 2.7.13
>  gcc (GCC) 6.2.0
> 
>  I attach the MG5 output file
> 
>  Thanks!
> 
>  Daniel
> 
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/mg5amcnlo/+bug/1716425/+subscriptions